Particularly when some good-natured sibling ribbing is the order of the day. When the E! stars sat down on The Tonight Show last night, the sisters gabbed about everything from Kanye West to the impending birth of Kourt's new baby girl to the rumors that Khloé was leaving the reality business to even—yes, they went there—Kim's still-fresh pending divorce.

That wasn't the only time Khloé got the best of Kim during the interview. While promoting the seventh season of Keeping Up With the Kardashians, which premieres Sunday at 9 p.m. on E!, Kim began rehashing the paternity drama that recently surrounded Khloé, explaining that her late father's exes were to blame for fanning the flames of the rumors.

"My dad's ex-wives that he was married to for two seconds..." Kim began, but Khloé quickly—and to applause, "oohs" and entertained gasps from the audience—said, "Runs in the family."

Oh yes, she went there. Kim good-naturedly rolled with the punch. "That was a good one," she said.

Meanwhile, Khloé also denied that her and Lamar Odom's temporary hiatus from their eponymous reality show signaled the beginning of the end for them on the small screen.

"I understand that people need to sell magazines," she said. "I didn't pull the plug on any show, we just wanted the summer [off].

"I mean, Lamar and I have fun doing what we're doing. Keeping Up is a show that we're taping and that we always do. I don't know how something spun so far out in the media. We're just doing what makes us happy, so until it doesn't make us happy, we'll do it. We're just taking the summer off. It's like we're in school, and now it's summer."

Which also means that the birth of Kourtney's second child is drawing ever closer. But can viewers expect to be treated to another video of the birth like her infamous footage delivering Mason?

"I don't know," she told Jay. "We're gonna film it again ourselves, and honestly, my experience last time was so peaceful and calm and everything you don't see in the movies. And I really wanted to share that with people so they knew it doesn't have to be a crazy screaming session."

Kourtney said that she and Scott Disick will decide after the fact "if we're into sharing it or not."

Now that would be must-see TV.

Tune in! Keeping Up With the Kardashians' seventh season premieres this Sunday at 9 p.m. on E!